Antiviral treatments

ABSTRACT

The invention provides unit dosage forms, kits, and methods and useful for treating viral infections.

RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.13/103,562, filed May 9, 2011 (pending). U.S. patent application Ser.No. 13/103,562 is a divisional application of U.S. application Ser. No.11/705,546, filed Feb. 12, 2007 (abandoned) and claims the benefit ofpriority of U.S. Application No. 60/772,748, filed Feb. 13, 2006,(expired) which applications are herein incorporated by reference.

BACKGROUND

The influenza virus neuraminidase inhibitor peramivir has markedactivity against the influenza virus in vitro and in experimentallyinfected mice (Govorkova et al., Antimicrobial Agents and Chemotherapy,45(10), 2723-2732 (2001); and Smee et al., Antimicrobial Agents andChemotherapy, 45(3), 743-748 (2001)). Unfortunately, clinical trialsusing this drug showed a suboptimal therapeutic effect on influenzainfection in humans following oral administration over a period of days.Currently there is a need for methods and formulations that are usefulfor treating viral infections (e.g., influenza infections) in humans.

SUMMARY OF THE INVENTION

It has unexpectedly been discovered that a single intravenousadministration of peramivir to a mouse is effective to treat influenza.These findings are unexpected not only because of the high effectivenessof a single administration of the compound, but also because of the lowdose of the compound that was found to provide effective treatment. Theability to obtain therapeutically useful effects with a singleadministration is important inter alia because it minimizes patientcompliance issues resulting from the need for multiple administrations.Additionally, the administration of a low dose is important because itminimizes cost and the potential for side-effects. It has also beenunexpectedly discovered that intravenous and intramuscular injections ofperamivir to humans provides high plasma concentrations of peramivirwith an extended half-life.

Accordingly, in one embodiment the invention provides a method fortreating a viral infection (e.g., an influenza infection) in a humancomprising administering an effective anti-viral amount of a compound offormula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, to the human by anintravenous route.

The invention also provides a method for inhibiting a neuraminidase in ahuman comprising administering an effective inhibitory amount of acompound of formula I, II, III, or IV, or a pharmaceutically acceptablesalt thereof, to the human by an intravenous route.

The invention also provides a unit dosage form that is suitable forintravenous administration to a human comprising up to about 400 mg of acompound of formula I, II, III, or IV, or a pharmaceutically acceptablesalt thereof.

The invention also provides a unit dosage form that is suitable forintravenous administration to a human comprising up to about 1,000 mg(e.g., up to about 800, 600, 500, 400, 300, 200, 150, 100, or 75 mg) ofa compound of formula I, II, III, or IV, or a pharmaceuticallyacceptable salt thereof.

The invention also provides a kit comprising packaging materials, acompound of formula I, II, III, or IV, or a pharmaceutically acceptablesalt thereof, and instructions for administering the compound to a humanby an intravenous route.

The invention also provides the use of a compound of formula I, II, III,or IV, or a pharmaceutically acceptable salt thereof, in the manufactureof a medicament for intravenous injection for increasing life expectancyor reducing mortality in a group of mammals exposed to a source of aninfluenza virus, by intravenous injection of a dose of the medicamentinto each member of the group presenting clinical symptoms of infection.

The invention also provides the use of a compound of formula I, II, III,or IV, or a pharmaceutically acceptable salt thereof, in the manufactureof a medicament for intravenous injection for increasing life expectancyor reducing mortality in a group of mammals exposed to a source of aninfluenza virus, by intravenous injection of a dose of the medicamentinto each member of the group.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1. FIG. 1 depicts plasma peramivir concentration time curves after15 minute intravenous infusions of peramivir to healthy humanvolunteers.

FIG. 2. FIG. 2 depicts plasma peramivir concentration time curves afterintramuscular injections of peramivir to healthy human volunteers.

DETAILED DESCRIPTION

The influenza virus neuraminidase inhibitor peramivir has beenpreviously shown to have marked activity against influenza virus invitro and in experimentally infected mice (Govorkova et al., (2001); andSmee et al., (2001)). Unfortunately, clinical trials using this drugshowed an inadequate inhibitory effect on influenza in humans. Thiseffect was attributed to a poor adsorption of the drug when administeredonce daily orally in patients.

It has been discovered that peramivir is well adsorbed when administeredintravenously (i.v.) in mice and that the compound remains at relativelyhigh levels in the plasma for at least 6 hours. A series of experimentspresented herein indicates that a single treatment of peramivir giveni.v. will protect mice infected with an influenza virus.

Accordingly, certain embodiments of the present invention provide amethod for treating a viral infection in a human comprisingadministering an effective anti-viral amount of a compound of formula I,II, III, or IV:

or a pharmaceutically acceptable salt thereof, to the human by anintravenous route.

In certain embodiments, the compound of formula I, II, III, or IV is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the viral infection is an influenza infection.In certain embodiments, the viral infection is an influenza type A ortype B infection. In certain embodiments, the viral infection is causedby a strain of virus represented by the formula H_(x)N_(y) wherein X isan integer from 1-16 and Y is an integer from 1-9. In certainembodiments, the influenza is an H3N2, H1N1, H5N1, avian, or seasonalinfluenza.

In certain embodiments, the effective anti-viral amount is up to about800 mg. In certain embodiments, the effective anti-viral amount is up toabout 400 mg. In certain embodiments, the effective anti-viral amount isup to about 300 mg. In certain embodiments, the effective anti-viralamount is up to about 200 mg.

In certain embodiments, the entire effective dose is administered in oneintravenous administration. In certain embodiments, the entire effectivedose is administered in multiple intravenous administrations.

In certain embodiments, a compound or formula Ia, or a pharmaceuticallyacceptable salt thereof, is administered.

In certain embodiments, the plasma concentration of the compound ishigher than the IC₅₀ of the virus causing the viral infection 12 hoursfollowing administration of the compound.

Certain embodiments of the present invention provide a method forinhibiting a neuraminidase in a human comprising administering aneffective inhibitory amount of a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, to the human by anintravenous route.

In certain embodiments, the compound of formula I, II, III, or IV is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the effective inhibitory amount is up to about800 mg. In certain embodiments, the effective inhibitory amount is up toabout 400 mg. In certain embodiments, the effective inhibitory amount isup to about 300 mg. In certain embodiments, the effective inhibitoryamount is up to about 200 mg.

In certain embodiments, the entire effective inhibitory dose isadministered in one intravenous administration. In certain embodiments,the entire effective inhibitory dose is administered in multipleintravenous administrations.

In certain embodiments, a compound of formula Ia, or a pharmaceuticallyacceptable salt thereof, is administered.

In certain embodiments, the methods may further comprise orallyadministering a neuraminidase inhibitor to the human.

In certain embodiments, the neuraminidase inhibitor that is administeredorally is oseltamivir carboxylate.

In certain embodiments, the neuraminidase inhibitor that is administeredorally is a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the neuraminidase inhibitor that is administeredorally is a compound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the neuraminidase inhibitor that is administeredorally is a compound of formula Ia, or a pharmaceutically acceptablesalt thereof.

In certain embodiments, the neuraminidase inhibitor that is administeredorally is administered for up to 20 days. In certain embodiments, theneuraminidase inhibitor that is administered orally is administered forup to 10 days. In certain embodiments, the neuraminidase inhibitor thatis administered orally is administered for up to 5 days.

Certain embodiments of the present invention provide a unit dosage formthat is suitable for intravenous administration to a human, comprisingup to about 800 mg of a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the compound of formula I, II, III, or IV is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the unit dosage form comprises up to about 400mg of the compound or salt. In certain embodiments, the unit dosage formcomprises up to about 300 mg of the compound or salt. In certainembodiments, the unit dosage form comprises up to about 200 mg of thecompound or salt.

Certain embodiments of the present invention provide a kit, comprisingpackaging materials, a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, and instructions foradministering the compound to a human by an intravenous route.

In certain embodiments, the compound is provided in a formulationsuitable for intravenous administration.

In certain embodiments, the kit comprises up to about 800 mg of thecompound or salt. In certain embodiments, the kit comprises up to about400 mg of the compound or salt. In certain embodiments, the kitcomprises up to about 300 mg of the compound or salt. In certainembodiments, the kit comprises up to about 200 mg of the compound orsalt.

Certain embodiments of the present invention provide a kit comprisingpackaging materials, a unit dosage form as described herein, andinstructions for administering the compound to a human by an intravenousroute.

Certain embodiments of the present invention provide a use of a compoundof formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intravenous injection for increasing life expectancy orreducing mortality in a group of mammals exposed to a source of aninfluenza virus, by intravenous injection of a dose of the medicamentinto each member of the group presenting clinical symptoms of infection.

In certain embodiments, the compound of formula I, II, III, or IV is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the influenza virus is an avian influenza virus.In certain embodiments, the influenza virus is an influenza type A ortype B virus. In certain embodiments, the influenza virus is H5N1, or amutant strain thereof. In certain embodiments, the influenza virus is astrain of virus represented by the formula H_(x)N_(y) wherein X is aninteger from 1-16 and Y is an integer from 1-9. In certain embodiments,the influenza virus is an H3N2, H1N1, H5N1, avian, or seasonal influenzavirus.

In certain embodiments, each member of the group presenting symptoms ofinfection receives only one intravenous dose of the medicament. Incertain embodiments, each member of the group presenting symptoms ofinfection receives multiple intravenous doses of the medicament.

In certain embodiments, the members of the group presenting clinicalsymptoms of infection are treated orally with a neuraminidase inhibitor.In certain embodiments, the neuraminidase inhibitor is oseltamivircarboxylate. In certain embodiments, the neuraminidase inhibitor is acompound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof. In certain embodiments,the neuraminidase inhibitor is a compound of formula Ia, IIa, IIIa, orIVa:

or a pharmaceutically acceptable salt thereof. In certain embodiments,the neuraminidase inhibitor is a compound of formula Ia, or apharmaceutically acceptable salt thereof.

In certain embodiments, the source of the virus is an infected bird. Incertain embodiments, the source of the virus is a mammal presentingsymptoms of infection.

In certain embodiments, the use is for reducing mortality.

Certain embodiments of the present invention provide a use of a compoundof formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intravenous injection for increasing life expectancy orreducing mortality in a group of mammals exposed to a source of aninfluenza virus, by intravenous injection of a dose of the medicamentinto each member of the group.

In certain embodiments, the compound of formula I, II, III, or IV is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

In certain embodiments, the influenza virus is an avian influenza virus.In certain embodiments, the avian influenza virus is H5N1, or a mutantstrain thereof. In certain embodiments, the influenza virus is a strainof virus represented by the formula H_(x)N_(y) wherein X is an integerfrom 1-16 and Y is an integer from 1-9. In certain embodiments, theinfluenza virus is an influenza type A or type B virus. In certainembodiments, the influenza virus is an H3N2, H1N1, H5N1, avian, orseasonal influenza virus.

In certain embodiments, each member of the group receives only oneintravenous dose of the medicament. In certain embodiments, each memberof the group receives multiple intravenous doses of the medicament.

In certain embodiments, the members of the group are treated orally witha neuraminidase inhibitor. In certain embodiments, the neuraminidaseinhibitor is oseltamivir carboxylate. In certain embodiments, theneuraminidase inhibitor is a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof. In certain embodiments,the neuraminidase inhibitor is a compound of formula Ia, IIa, IIIa, orIVa:

or a pharmaceutically acceptable salt thereof. In certain embodiments,the neuraminidase inhibitor is a compound of formula Ia, or apharmaceutically acceptable salt thereof.

In certain embodiments, the source of the virus is an infected bird. Incertain embodiments, the source of the virus is a mammal presentingsymptoms of infection.

In certain embodiments, the use is for reducing mortality.

Certain embodiments of the present invention provide a use of a compoundof formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intravenous injection for achieving a plasmaconcentration in a human of the compound that is effective to treat avirus by intravenous injection of a dose of the medicament into thehuman.

Certain embodiments of the present invention provide a use of a compoundof formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intramuscular injection for achieving a plasmaconcentration in a human of the compound that is effective to treat avirus by intramuscular injection of a dose of the medicament into thehuman.

In certain embodiments, the plasma concentration of the compound ishigher than the IC₅₀ of the virus 12 hours following injection of thecompound.

Mice infected with influenza A/Duck/MN/1525/81 (H5N1) virus were treateda single time i.v. 1 hour pre-virus exposure with peramivir at doses of20, 10 and 3 mg/kg. Peramivir was significantly protective to the miceat the two highest dosages used, as seen by prevention of deaths,lessening of lung consolidation, and inhibition of lung virus titers.The 3 mg/kg dose was moderately inhibitory to lung parameters. Thecompound appeared well tolerated in concomitantly run toxicity controls.These data indicate that a single i.v. peramivir treatment isefficacious in influenza virus-infected mice.

The compounds used in the invention are known in the art and can besynthesized by the art worker using available methods (see, e.g., U.S.Pat. No. 6,562,861).

Specific values listed herein for radicals, substituents, and ranges,are for illustration only; they do not exclude other defined values orother values within defined ranges for the radicals and substituents

A specific compound of formula I, II, III, or IV is a compound offormula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.

A specific compound of formula I, II, III, or IV is(1S,2S,3R,4R)-3-(1-Acetamido-2-ethylbutyl)-4-guanidino-2-hydroxycyclopentane-carboxylicacid;(1S,2S,3R,4R)-3-(1-Acetamido-2-propylpentyl)-4-guanidino-2-hydroxycyclopentanecarboxylicacid;(1R,3R,4R)-3-(1-Acetamido-2-propylpentyl)-4-guanidinocyclopentanecarboxylicacid; or(1R,3R,4R)-3-(1-Acetamido-2-ethylbutyl)-4-guanidinocyclopentanecarboxylicacid; or a pharmaceutically acceptable salt thereof.

A specific compound of formula I is a compound of formula Ia, or apharmaceutically acceptable salt thereof.

It will be appreciated by those skilled in the art that compounds havingone or more chiral centers may exist in and be isolated in opticallyactive and racemic forms. Some compounds may exhibit polymorphism. It isto be understood that the present invention encompasses the use of anyracemic, optically-active, polymorphic, or stereoisomeric form, ormixtures thereof, of a compound of formula I, II, III, or IV, whichpossess the useful properties described herein, it being well known inthe art how to prepare optically active forms (for example, byresolution of the racemic form by recrystallization techniques, bysynthesis from optically-active starting materials, by chiral synthesis,or by chromatographic separation using a chiral stationary phase) andhow to determine anti-viral (e.g. anti-influenza) activity using thestandard tests described herein, or using other similar tests which arewell known in the art.

In cases where compounds are sufficiently basic or acidic to form stablenontoxic acid or base salts, administration of the compounds as saltsmay be appropriate. Examples of pharmaceutically acceptable salts areorganic acid addition salts formed with acids which form a physiologicalacceptable anion, for example, tosylate, methanesulfonate, acetate,citrate, malonate, tartarate, succinate, benzoate, ascorbate,α-ketoglutarate, and α-glycerophosphate. Suitable inorganic salts mayalso be formed, including hydrochloride, sulfate, nitrate, phosphate,bicarbonate, and carbonate salts.

Pharmaceutically acceptable salts may be obtained using standardprocedures well known in the art, for example by reacting a sufficientlybasic compound such as an amine with a suitable acid affording aphysiologically acceptable anion. Alkali metal (for example, sodium,potassium or lithium) or alkaline earth metal (for example calcium)salts of carboxylic acids can also be made.

The compounds of formula I, II, III, and IV can be formulated aspharmaceutical compositions and administered to a mammalian host, suchas a human patient, by intravenous routes. Solutions of the activecompound or its salts can be prepared in water, optionally mixed with anontoxic surfactant. Dispersions can also be prepared in glycerol,liquid polyethylene glycols, triacetin, and mixtures thereof and inoils. Under ordinary conditions of storage and use, these preparationscontain a preservative to prevent the growth of microorganisms.

The pharmaceutical dosage forms suitable for injection or infusion caninclude sterile aqueous solutions or dispersions or sterile powderscomprising the active ingredient(s) which are adapted for theextemporaneous preparation of sterile injectable or infusible solutionsor dispersions, optionally encapsulated in liposomes. In all cases, theultimate dosage form should be sterile, fluid and stable under theconditions of manufacture and storage. The liquid carrier or vehicle canbe a solvent or liquid dispersion medium comprising, for example, water,ethanol, a polyol (for example, glycerol, propylene glycol, liquidpolyethylene glycols, and the like), vegetable oils, nontoxic glycerylesters, and suitable mixtures thereof. The proper fluidity can bemaintained, for example, by the formation of liposomes, by themaintenance of the required particle size in the case of dispersions orby the use of surfactants. The prevention of the action ofmicroorganisms can be brought about by various antibacterial andantifungal agents, for example, parabens, chlorobutanol, phenol, sorbicacid, thimerosal, and the like. In many cases, it will be preferable toinclude isotonic agents, for example, sugars, buffers or sodiumchloride. Prolonged absorption of the injectable compositions can bebrought about by the use in the compositions of agents delayingabsorption, for example, aluminum monostearate and gelatin. Sterileinjectable solutions can be prepared by incorporating the activecompound(s) into an appropriate solvent with the other optionalingredients enumerated above, optionally followed by filtersterilization. In the case of sterile powders for the preparation ofsterile injectable solutions, the preferred methods of preparation arevacuum drying and the freeze drying techniques, which yield a powder ofthe active ingredient plus any additional desired ingredient present inthe previously sterile-filtered solutions.

As used herein the terms “treat”, “treating” and “treatment” includeadministering a compound prior to the onset of clinical symptoms of adisease state/condition so as to prevent the development of any symptom,as well as administering a compound after the onset of one or moreclinical symptoms of a disease state/condition so as to reduce oreliminate any such symptom, aspect or characteristic of the diseasestate/condition. Such treating need not be absolute to be useful. Asillustrated hereinbelow, the active compounds can be administered priorto exposure to the virus. The agents can also be administered subsequent(e.g., within 1, 2, 3, 4, or 5 days) to exposure to the virus.

As used herein the term “unit dosage form” relates to an intravenousformulation containing a specific amount of a drug, the whole of whichis intended to be administered as a single dose. It is distinguishedfrom a supply of an indefinite amount of a medicament, e.g., a bottle ofmedicine, from which a dose has to be measured out.

In one embodiment the invention provides a method for treating a viralinfection in a human comprising administering an effective amount of acompound of formula I, II, III, or IV, or a pharmaceutically acceptablesalt thereof, to the human by intravenous administration. Typically, theeffective amount is administered in a single intravenous administration.In some embodiments, the effective amount is administered in multipleadministrations. Accordingly, the methods of the invention provide forhigh patient compliance and they require a low dose of the effectiveagent.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 1,000 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 800 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 600 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 500 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 400 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 300 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 200 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 150 mg.

In one embodiment of the invention, the effective inhibitory amount ofthe compound of formula I, II, III, or IV is up to about 75 mg.

According to the methods of the invention a compound of formula I, II,III, or IV is administered to a human intravenously. In one embodimentof the invention, the compound of formula I, II, III, or IV isadministered once to a human intravenously. In another embodiment of theinvention, a neuraminidase inhibitor is also administered to the humanorally. In one embodiment of the invention, the neuraminidase inhibitorthat is administered orally is oseltamivir carboxylate. In oneembodiment of the invention, the neuraminidase inhibitor that isadministered orally is a compound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof. In one embodiment of theinvention, the neuraminidase inhibitor that is administered orally is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof. In one embodiment of theinvention, the neuraminidase inhibitor that is administered orally is acompound of formula Ia, or a pharmaceutically acceptable salt thereof.

According to the methods of the invention, the compound of formula I,II, III, or IV, or a pharmaceutically acceptable salt thereof, can alsobe administered in combination with one or more additional therapeuticagents, such as anti-viral agents (e.g., agents active againstinfluenza) or antibiotics.

The intravenous formulations of the invention can also comprise one ormore additional therapeutic agents, such as anti-viral agents (e.g.,agents active against influenza) and antibiotics.

Thus, intravenous administration of peramivir to treat a viral infectionis described herein. Intramuscular administration of peramivir to treata viral infection is also described herein (see, e.g., Example 2), whichfurther exemplifies intramuscular administration of peramivir to treat aviral infection, as is described in International Application No.PCT/US2006/013535, filed Apr. 12, 2006, the disclosure of which isincorporated by reference. Further, as described herein, it has beenunexpectedly discovered that intravenous and intramuscular injections ofperamivir to humans provides high plasma concentrations of peramivirwith an extended plasma half-life.

As described herein, the compounds described herein can be used to treata virus, e.g., an influenza virus. For example, the compounds can beused to treat any one or combination of the following strains. In thetable below, the “H” stands for a type of hemagglutinin, and the “N”stands for a type of neuraminidase. The formula H_(x)N_(y) wherein X isan integer from 1-16 and Y is an integer from 1-9, can also be used todescribe the combinations presented in the table.

TABLE 1 N1 N2 N3 N4 N5 N6 N7 N8 N9 H1 H1N1 H1N2 H1N3 H1N4 H1N5 H1N6 H1N7H1N8 H1N9 H2 H2N1 H2N2 H2N3 H2N4 H2N5 H2N6 H2N7 H2N8 H2N9 H3 H3N1 H3N2H3N3 H3N4 H3N5 H3N6 H3N7 H3N8 H3N9 H4 H4N1 H4N2 H4N3 H4N4 H4N5 H4N6 H4N7H4N8 H4N9 H5 H5N1 H5N2 H5N3 H5N4 H5N5 H5N6 H5N7 H5N8 H5N9 H6 H6N1 H6N2H6N3 H6N4 H6N5 H6N6 H6N7 H6N8 H6N9 H7 H7N1 H7N2 H7N3 H7N4 H7N5 H7N6 H7N7H7N8 H7N9 H8 H8N1 H8N2 H8N3 H8N4 H8N5 H8N6 H8N7 H8N8 H8N9 H9 H9N1 H9N2H9N3 H9N4 H9N5 H9N6 H9N7 H9N8 H9N9 H10 H10N1 H10N2 H10N3 H10N4 H10N5H10N6 H10N7 H10N8 H10N9 H11 H11N1 H11N2 H11N3 H11N4 H11N5 H11N6 H11N7H11N8 H11N9 H12 H12N1 H12N2 H12N3 H12N4 H12N5 H12N6 H12N7 H12N8 H12N9H13 H13N1 H13N2 H13N3 H13N4 H13N5 H13N6 H13N7 H13N8 H13N9 H14 H14N1H14N2 H14N3 H14N4 H14N5 H14N6 H14N7 H14N8 H14N9 H15 H15N1 H15N2 H15N3H15N4 H15N5 H15N6 H15N7 H15N8 H15N9 H16 H16N1 H16N2 H16N3 H16N4 H16N5H16N6 H16N7 H16N8 H16N9The virus may be, for example, an avian virus or a humanized avianvirus. Thus, the term “avian virus” includes both avian forms of thevirus and humanized forms of the avian virus.

Certain embodiments of the present invention provide the use of acompound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intravenous injection for achieving a plasmaconcentration in a human of the compound that is effective to treat avirus by intravenous injection of a dose of the medicament into thehuman.

Certain embodiments of the present invention also provide the use of acompound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof, in the manufacture of amedicament for intramuscular injection for achieving a plasmaconcentration in a human of the compound that is effective to treat avirus by intramuscular injection of a dose of the medicament into thehuman.

Certain embodiments of the invention also provide compositionscomprising peramivir formulated for intravenous administration to ahuman. Certain embodiments of the invention also provide compositionscomprising peramivir formulated for intravenous administration for usein treating a virus by achieving a plasma concentration in a human ofperamivir that is effective to treat the virus.

Certain embodiments of the invention also provide compositionscomprising peramivir formulated for intramuscular administration to ahuman. Certain embodiments of the invention also provide compositionscomprising peramivir formulated for intramuscular administration for usein treating a virus by achieving a plasma concentration in a human ofperamivir that is effective to treat the virus.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 12 hoursfollowing the injection.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 24 hoursfollowing the injection.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 36 hoursfollowing the injection.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 48 hoursfollowing the injection.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 60 hoursfollowing the injection.

In certain embodiments of the invention, the plasma concentration of thecompound is higher than the IC₅₀ of the virus at least about 72 hoursfollowing the injection.

In certain embodiments of the invention, the virus is an influenzavirus. In certain embodiments of the invention, the virus is an avianinfluenza virus. In certain embodiments of the invention, the virus isH5N1, or a mutant strain thereof.

The invention will now be illustrated by the following non-limitingExamples.

Example 1 Effect of IV Treatment with Peramivir on Influenza a VirusInfection

Experiment Design:

Mice were infected i.n. with a dose thought to be the LD100 of influenzavirus. Groups of 10 mice were treated i.v. with peramivir at dosages of20, 10 and 3 mg/kg a single time 1 hour pre-virus exposure. Placebo(sterile saline) was administered i.v. in parallel with the above to 20infected mice. Drug-treated infected mice and placebo-treated controlswere observed daily for death through 21 days. As toxicity controls, 3uninfected mice were treated with the highest dose of the compounds inparallel to the infected animals. All toxicity controls were observedfor death through 21 days and were weighed immediately prior to theinitial treatment and 18 h after the final treatment. Five normalcontrols were weighed.

TABLE 2 Effect of Single I.V. Treatment with Peramivir on an Influenza AVirus Infection in Mice. Animals: Female 18-21 gram Treatment schedule:Peramivir,: Single BALB/c mice treatment 1 hour pre-virus exposureVirus: Influenza Treatment route: Peramivir i.v.; A/Duck/MN/152518(H5N1) Expt. duration: 21 days Drug diluent: Sterile Saline ToxInfected, Treated Mice Controls Mean Day Dose Surv/ Surv/ to Death^(b) ±Treatment (mg/kg) Total Total SD Peramivir 20 3/3 10/10** >21.0 ± 0.0***10 3/3 10/10** >21.0 ± 0.0*** 3 3/3 5/10  9.6 ± 1.3 Saline — — 9/20  9.1± 1.4 Normal — 5/5 — — Controls ^(b)Mean day to death of mice dyingprior to day 21. **P < 0.01; ***P < 0.001 compared to saline-treatedcontrols.The infection induced in this experiment was lethal to 55% of the mice(Table 1), with a mean day to death of 9.1 days. The single i.v.injection with peramivir at 20 and 10 mg/kg was highly protective to theinfected animals, with 100% surviving the infection (P<0.01). Toxicitycontrols run in parallel all survived and gained weight, indicatingcompound was well tolerated in this experiment.

These data indicate that peramivir is a significant influenza inhibitorwhen used in a single i.v. injection.

Example 2 Effects of IV and IM Treatment with Peramivir in Humans

Peramivir was studied in a placebo-controlled phase I clinical study inhealthy human volunteers to evaluate safety and pharmacokineticparameters using intravenous and intramuscular administrations. Bloodsamples were collected from the subjects at different time points afterdrug administration to determine the concentration of the drug inplasma. The time course plots are shown in FIG. 1 and FIG. 2 forintravenous and intramuscular administrations respectively.

In the intravenous study, peramivir concentrations followed linearkinetics with an unusually extended plasma half life of greater than 12hours. At doses of 2 mg/kg and above, the level of peramivir in plasmaat 48 hours post-dose is greater than the IC₅₀ for all strains ofinfluenza virus tested, including H5 virus types. For doses greater than4 mg/kg, even at 72 hours, the levels of the drug are greater than theIC₅₀ values.

In the intramuscular study, peramivir concentrations also followedlinear kinetics with an unusually extended plasma half life. Even at 72hours post-dosing, the levels of peramivir are higher than the IC₅₀values for all the influenza virus strains tested.

The long plasma half-life and the high levels of peramivir in humanvolunteers are unusual and unexpected findings and indicate thatintravenous and intramuscular administrations of peramivir arebeneficial in the treatment of influenza in humans.

All publications, patents and patent applications cited herein areincorporated herein by reference. While in the foregoing specificationthis invention has been described in relation to certain embodimentsthereof, and many details have been set forth for purposes ofillustration, it will be apparent to those skilled in the art that theinvention is susceptible to additional embodiments and that certain ofthe details described herein may be varied considerably withoutdeparting from the basic principles of the invention.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention are to be construed to cover boththe singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The terms “comprising,” “having,”“including,” and “containing” are to be construed as open-ended terms(i.e., meaning “including, but not limited to”) unless otherwise noted.Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed.

What is claimed is:
 1. A method for treating a viral infection in ahuman comprising administering in a single intravenous administrationper day over the course of treatment an effective anti-viral amount of acompound of formula I:

or a pharmaceutically acceptable salt thereof, to the human.
 2. Themethod of claim 1, wherein the compound of formula I is a compound offormula Ia:

or a pharmaceutically acceptable salt thereof.
 3. The method of claim 1,wherein the viral infection is an influenza type A or type B infection.4. The method of claim 1, wherein the influenza infection is caused by astrain of virus represented by the formula H_(x)N_(y) wherein X is aninteger from 1-16 and Y is an integer from 1-9
 5. The method of claim 1,wherein the influenza is an H3N2, H1N1, H5N1, avian, or seasonalinfluenza.
 6. The method of claim 1, wherein the effective anti-viralamount is up to about 800 mg per day.
 7. The method of claim 8, whereinthe effective anti-viral amount is up to about 600 mg per day.
 8. Themethod of claim 9, wherein the effective anti-viral amount is up toabout 300 mg per day.
 9. The method of claim 1, wherein the effectiveanti-viral amount is about 150 mg per day.
 10. The method of claim 1,wherein the plasma concentration of the compound is higher than the IC₅₀of the virus causing the viral infection 12 hours followingadministration of the compound.
 11. The method of claim 1, furthercomprising orally administering a neuraminidase inhibitor to the human.12. The method of claim 11, wherein the neuraminidase inhibitor that isadministered orally is oseltamivir carboxylate.
 13. The method of claim11, wherein the neuraminidase inhibitor that is administered orally is acompound of formula I, II, III, or IV:

or a pharmaceutically acceptable salt thereof.
 14. The method of claim11, wherein the neuraminidase inhibitor that is administered orally is acompound of formula Ia, IIa, IIIa, or IVa:

or a pharmaceutically acceptable salt thereof.
 15. The method of claim14, wherein the neuraminidase inhibitor that is administered orally is acompound of formula Ia, or a pharmaceutically acceptable salt thereof.16. The method of claim 11, wherein the neuraminidase inhibitor that isadministered orally is administered for up to 20 days.
 17. The method ofclaim 11, wherein the neuraminidase inhibitor that is administeredintravenously is administered for up to 5 days or up to 10 days.
 18. Akit, comprising packaging materials, a compound of formula Ia:

or a pharmaceutically acceptable salt thereof, and instructions foradministering the compound to a human in a single intravenousadministration per day over the course of treatment to treat aninfluenza infection.
 19. The kit of claim 18 wherein the compound orsalt is provided in a unit dose sufficient for a single administrationper day.
 20. The kit of claim 19, wherein the unit dose comprises up toabout 800 mg of the compound or salt, up to about 600 mg of the compoundor salt, up to about 300 mg of the compound or salt or up to about 150mg of the compound or salt.
 21. A method for increasing life expectancyor reducing mortality in a group of humans exposed to a source of aninfluenza virus, comprising administering to members of the grouppresenting clinical symptoms of an influenza infection in a singleintravenous administration per day over the course of treatment, aneffective anti-viral amount of a compound of formula I:

or a pharmaceutically acceptable salt thereof.